


Can't Help Myself

by OopsIShipTheThingArchive



Category: Big Hero 6 (2014)
Genre: Alternate Universe - Canon Divergence, Hand Jobs, M/M, Plot What Plot/Porn Without Plot, Shameless Smut, Sibling Incest
Language: English
Status: Completed
Published: 2014-11-26
Updated: 2014-11-26
Packaged: 2018-02-27 02:24:44
Rating: Mature
Warnings: Underage
Chapters: 1
Words: 2,506
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2675420
Author URL: https://archiveofourown.org/users/OopsIShipTheThingArchive/pseuds/OopsIShipTheThingArchive
Summary: <blockquote class="userstuff">
              <p>Hiro can always tell when Tadashi's starting to have doubts.  The fact that eliminating those doubts happens to involve getting off--well, that's just a happy coincidence.</p>
            </blockquote>





	Can't Help Myself

**Author's Note:**

> DISCLAIMER: I am fully aware of how problematic this ship is, and why. I am very, very careful about how I write it. If you have a suggestion for me on how to handle it better please, I am open to suggestions.  
> That said, where the hell did this new incest ship come from and why? Help me.  
> Also in this universe Tadashi is alive and the fire never happened because I damn well say so.

There was no way Tadashi was going to get out of this without needing serious therapy.  And he knew full well that the one who was going to be damaged by this was Hiro (poor Hiro), but there was something rather mentally destabilizing about being regularly seduced by one’s younger brother.

Every single time Tadashi knew he should make this stop, contemplated increasingly drastic measures including therapy under an assumed name and (in his low points) turning himself over to police.

But then Hiro, far too perceptive, far too stubborn Hiro, would catch him up in a whirlwind of kisses and tender touches and soft cries in the dark, and every single time he fell right back into it.

Not that Tadashi was unwilling, oh no, he was far too willing and it was far too easy to give in when Hiro was determined to bend—always bend, never break, he knew Tadashi would never allow that—the careful rules that Tadashi had laid down when they started this…whatever this was.

Today was one of those days, when Tadashi had awoken to his sleepy-eyed brother slipping out of his arms and back to his own bed before their aunt could come in to wake both of them for class. Tadashi smiled when Hiro pressed a light kiss to his cheek, and then rolled over to face the wall and tried to go back to sleep.

The key word being _tried_.  He kept seeing Hiro’s face in his mind’s eye, large eyes alight with adoration even when they were half-lidded with the early hour.  And then Hiro as he’d looked last night, mouth slack and body arching and sheened with sweat and—

Tadashi needed a shower. A cold one.  He waited for Hiro’s breathing to even out again as he dropped back into sleep before he crept out to their shared bathroom, resigning himself to another day of self doubt and borderline loathing.

***

Really, he should have known that Hiro knew exactly what he’d been thinking throughout the day. And he should have expected the subtle click of the lock of their bedroom door after dinner, while Aunt Cass was loudly washing dishes in the kitchen and he’d gone upstairs on the pretense of having homework he needed to do.

He had no idea what excuse Hiro had used, now that Cass had cottoned on to the fact that stupid genius boy never had any homework that he hadn’t finished at school.  He’d probably just wandered up here with no explanation, which meant that she would be looking for him soon.

Content in his perfectly reasonable and indisputable reason not to give in to his brother’s wanton ways, Tadashi raised his book higher and pretended he didn’t notice the slight dip in the mattress as Hiro sat down next to him.   Several silent moments passed, long enough that the hard headboard against his back was beginning to be uncomfortable, and he knew Hiro would be doing his best sad-face at the back of his physics textbook—which he realized, rather belatedly, was upside down.

So much for subtlety. But he still wasn’t about to give in, because he knew he could always beat Hiro at a game of patience. And sure enough the text was soon obscured by wild hair and big brown eyes.

“You’re doing it again, Tadashi,” he said accusingly.

Tadashi raised an eyebrow. “Doing what?”

Hiro scowled and puffed out his cheeks.  “Making yourself feel bad again."

Well.  No answer to that.  He settled for raising his textbook weakly.  “I actually do have studying to do.  And Aunt Cass will be up here looking for you to help her in the café any minute now.”

Now Hiro’s smile was just a little too satisfied.  “No she won’t, I told her I needed to work on my microbots for a final project and I need peace and quiet for the whole night.  So she will be leaving us alone completely.”

“And why do we want to be left alone?”  Tadashi asked calmly. Oh, now he was doing it again, riling his little brother on purpose when he knows where it will lead every time. The smile dropped from Hiro’s face; there was nothing that annoyed him more than Tadashi pretending that he was oblivious to Hiro’s attempts to get in his pants.

“You know exactly why, don’t do that,” he grumbled, clambering over to straddle Tadashi’s stomach and trace the planes of his chest through his tee-shirt, and he can’t help the way his breath hitches.

Dammit.

Sometimes he thinks that Hiro keeps a mental or even physical list of all the things he’d done and Tadashi’s exact reactions to them.  Then Hiro leaned forward and traced his tongue around the shell of his ear and through his whole-body shudders he thought that was a silly thing to wonder about. Of course Hiro kept just such a list.

Hiro didn’t let up on his ears until he was panting and incoherent, but then finally backed up to let him breathe. “Stop trying to act like I don’t know what I’m doing, Tadashi,” he said firmly.  “I know exactly, and I know that you worry about hurting me and if it ever gets too hard for you you _know_ I’ll stop but…I don’t want to.”  He looked up under long dark lashes, uncertainty creeping into his gaze for the first time, and he had never been able to resist reassuring his brother when he looked like that.

“I’m supposed to be the one taking care of you, not the other way around.” Tadashi commented, bracing his hands on Hiro’s waist before he could try to distract him again.

The younger pouted. “Yeah, well, sometimes you need taking care of too.  And—“ his entire face lit up with his smile—“who better to do that than me?”

Tadashi just watched him, waiting, almost able to see the cogs turning in his brother’s head. Always, always planning how to get a reaction out of him, but he wasn’t going to give a single hint this time.

Finally Hiro let out a groan of frustration, leaning forward and capturing him in a demanding kiss, managing to clack their teeth together with the force of it and oh damn him Tadashi was never meant to resist this.  Not to mention that the way Hiro tilted his hips and rocked against him just a little left no doubt as to his brother’s state.

Tadashi couldn’t help the rather inelegant snort he let out.  “Really?  Even after last night?”

Hiro made a face as he pulled away, but the insistent little rolls of his hips didn’t slow. “Don’t, Tadashi. I just…please?”

Dammit.  Dammit dammit _dammit_.

His hands that had been desperately trying to keep Hiro still were now pushing and pulling and automatically adjusting to the rhythm he knew drove Hiro absolutely mad.

“So the goal here was to convince me that you know what you’re doing and I shouldn’t worry about you right?” Hiro nodded, looking extremely self-satisfied.  “So when did getting off become part of the equation?”

Now he reached around and grasped, spreading Hiro through his pants, and gaining a long high noise for his trouble.  “Hah—just a nice bonus to making you feel better,” Hiro gasped, trying to smirk and failing as Tadashi released him just long enough to hook a finger through the waistband of his khakis and flicking the button open with his other hand. Hiro squirmed, working his pants down to his knees before kicking one leg up and waiting for Tadashi to pull them all the way off.

The elder obliged, pressing a kiss to the inside of one bony ankle before it was yanked away with a giggle, ignored the tented boxers that Hiro clearly was trying to direct his attention to and instead reached for the hem of his shirt.  Hiro huffed at him, but didn’t push, probably aware that moving too fast would make Tadashi start questioning whether they should be doing this. He appreciated it, even though it took all of ten seconds between the removal of his shirt and Hiro starting to wriggle impatiently again.

Tadashi rolled his eyes, pushing him up to a kneeling position in his lap and kissing down his skinny chest while he slowly, excruciatingly worked the boxers down thin hips. He had yet to touch him anywhere sensitive and yet Hiro was already panting, shaking fingers weaving into his hair and tightening with anticipation.

As soon as the underwear were as far down Hiro’s spread legs as he could get them without shifting him Tadashi allowed himself a smirk—and flicked his tongue into Hiro’s bellybutton. The boy shrieked, tumbling backwards over Tadashi’s legs.

Tadashi was barely able to shush him through his giggles.  “Don’t get Aunt Cass up here yelling at me to leave you alone so you can do your important genius things.”

Hiro tried to scowl at him, shoving upright with a mutter that sounded suspiciously like “I’ll show you important genius things.”  But as he was sitting up he managed to flick his boxers off the one ankle they were still hanging on and now all Tadashi had to touch was soft skin and hard angles and Hiro gasped as Tadashi finally—finally—wrapped a hand around him and stroked just once. His entire body stuttered as his head flopped forward to land with a thump on Tadashi’s shoulder.

Tadashi contained his amusement, barely, mostly because the noises Hiro was now making right next to his ear were absolutely delicious and he had to concentrate very hard on not reacting. Then there were hands creeping up under his shirt and he couldn’t feign indifference anymore. “H-hiro,” he said warningly, pretending his hips hadn’t given a small involuntary buck.

Hiro’s response was a breathy chuckle and the slight pressure of teeth against his skin through his shirt. “I’m not going to take it _off_ , Tadashi, just exploring,” he muttered, hands never ceasing their fevered movements across Tadashi’s bare skin, every touch leaving a trail of heat in its wake.

Very well. Two could play at that game. Tadashi never stopped his incessant rhythm, never missed a beat as he pulled Hiro tauter and tauter, closer and closer. With his free arm he pulled his brother in close to his body, trapping him between the friction of his strokes, the shifting cloth of his shirt, and firm pressure at his back.

Hiro was rutting wildly into the touches, but he still hadn’t completely given up all control. That wouldn’t do at all. Sudden inspiration struck as Hiro’s hands worked their way around to his back and started leaving scratch marks down his shoulder blades.  He released his hold around his back and trailed his hand lower, Hiro whining as he had to shift his limbs to compensate, then freezing completely as the light touch continued down to trace the dimples of his lower back.

Tadashi continued lower, and halted when Hiro stopped _breathing._ “Okay?” he whispered, fairly sure he knew what the answer was, and he was immediately validated when Hiro nodded so hard against his shoulder that he nearly brained himself on Tadashi’s collarbone.

Tadashi smiled, rewarding him with a stroke down his cleft and ever-so-light brush across the puckered skin of his entrance.  Hiro tensed, wound so tight he couldn’t even _whine_ and his entire body jerked as Tadashi circled his finger first one way then the other.  Then he resumed stroking, faster and tighter than before, and the hands on his back were just scrabbling for something to hold on to, not meant to inflame anymore and yet it was so rawly arousing, watching Hiro fall apart in his arms.

His head tipped back as his back arched, barely able to focus on Tadashi’s face as he moaned. “Ta…da…shi…so good…love—“

He didn’t want to hear it. He twisted his wrist and swallowed Hiro’s high noise as the younger melted into his grip.

“Come on,” he murmured, picking up the pace and pressing just a little harder against the center of that little pucker.  “Come on, Hiro.”

It was the sound of his name that got him, it always was, and Hiro sank his teeth into Tadashi’s shoulder to barely muffle his cry as he came, hips stuttering and warm spurts wetted Tadashi’s hand and tee-shirt.

It took him long moments to come down, moments Tadashi spent lightly combing that wild mane of hair and gently rearranging their limbs into a more comfortable configuration. He had to admit, he loved these times far too much, the way Hiro finally stopped thinking, calculating, planning for just a few seconds.

A shaky giggle and hands pushing him away from the soft hair he loved so much alerted him to Hiro’s return to reality.  And also drew attention to the fact that he was still painfully aroused.  Hiro slowly sank down until he was seated in Tadashi’s lap and only when his eyes shot wide did Tadashi realize just what Hiro could feel brushing between his cheeks.

He knew he was blushing furiously, and refused to react to the triumphant grin that spread across Hiro’s face. “Your turn?” He asked, all hopeful innocence, fingers already dipping below his waistband before Tadashi captured both his wrists in one hand.

“Not until—“ he began.

Hiro rolled his eyes and completed it for him.  “Not until both of us have calmed down enough that it won't go too far, I _know_ ,” he sulked.  “Come on, you’re not tempted to let that go just this once?”

Then those teeth were nibbling at his ear again, the little _fiend_ , and Tadashi’s head thumped back into the headboard with an ‘ow!’ that was more surprise than pain.

All in the same instant he realized what he’d said, Hiro’s eyes went wide with horror, and there was a terrible whooshing noise from the communal area of their bedroom. By the time Baymax had fully inflated and waddled around their divider Hiro had literally burrowed under the blankets and Tadashi had grabbed a pillow and was clutching it to his lap and over the wet spot on his tee-shirt.

“I heard a sound of—“

“Yes Baymax, thank you, we’re fine, you can deactivate now,” Tadashi said loudly.

“Your heart rate and temperature are elevated—“

“Baymax!  We’re satisfied with our care!  Deactivate!”

The robot blinked slowly before wandering back to his case, thankfully not diagnosing either of them out loud. He’d removed that function after the time Baymax had begun listing the puberty symptoms Hiro was experiencing in front of his older brother.

When he heard the click of Baymax’s case shutting down he glanced over at the top of Hiro’s head—all he could see as the boy peeked cautiously out from under the blankets—and had to stifle a peal of slightly hysterical laughter.

Dear god, forget therapy. There was probably nothing to be done about either of their mental states now.

**Author's Note:**

> This started out as a 500 word drabble that ended when Baymax interrupted them before anyone even lost their pants and now it's 2500 words of plotless smut. How do these things happen to me?


End file.
